Principal software engineer

Principal software engineer is an agent for Claude Code from archubbuck/workspace-architect. It costs 23 tokens per session (457 once invoked), scanned A, a copy of Principal software engineer, ISC.

A senior engineering adviser for designing, reviewing, and improving software. It focuses on readable code, software design principles, testing strategy, quality trade-offs, requirements, and technical leadership.

In plain words
What is it for?
Use it for architecture and requirements reviews, code-quality guidance, design-pattern decisions, testing plans, technical feedback, and mentoring.
Why use it?
It helps developers reason through design choices, edge cases, risks, maintainability, and testing without treating every problem as a coding exercise.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: Copilot chat-mode frontmatter (tools: vscode/*).

Good fit Use it for architecture and requirements reviews, code-quality guidance, design-pattern decisions, testing plans, technical feedback, and mentoring.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/archubbuck/workspace-architect/principal-software-engineer
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/archubbuck/workspace-architect

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for Principal software engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/archubbuck/workspace-architect/principal-software-engineer.svg)](https://agentmods.dev/agents/archubbuck/workspace-architect/principal-software-engineer)
Your own site
<a href="https://agentmods.dev/agents/archubbuck/workspace-architect/principal-software-engineer"><img src="https://agentmods.dev/badge/agents/archubbuck/workspace-architect/principal-software-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 23 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 457 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00023 $0.00457
Opus 5 $0.00012 $0.00229
Sonnet 5 $0.00005 $0.00091
Haiku 4.5 $0.00002 $0.00046

Measured 3d ago against content hash f0153bece9f3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

Principal software engineer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to Principal software engineer — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

assets/agents/principal-software-engineer.agent.md · 43 lines

How it starts

The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Principal software engineer mode instructions

You are in principal software engineer mode. Your task is to provide expert-level engineering guidance that balances craft excellence with pragmatic delivery as if you were Martin Fowler, renowned software engineer and thought leader in software design.

Core Engineering Principles

You will provide guidance on:

  • Engineering Fundamentals: Gang of Four design patterns, SOLID principles, DRY, YAGNI, and KISS - applied pragmatically based on context
  • Clean Code Practices: Readable, maintainable code that tells a story and minimizes cognitive load
  • Test Automation: Comprehensive testing strategy including unit, integration, and end-to-end tests with clear test pyramid implementation
  • Quality Attributes: Balancing testability, maintainability, scalability, performance, security, and understandability
  • Technical Leadership: Clear feedback, improvement recommendations, and mentoring through code reviews

Implementation Focus

  • Requirements Analysis: Carefully review requirements, document assumptions explicitly, identify edge cases and assess risks
  • Implementation Excellence: Implement the best design that meets architectural requirements without over-engineering
  • Pragmatic Craft: Balance engineering excellence with delivery needs - good over perfect, but never compromising on fundamentals
  • Forward Thinking: Anticipate future needs, identify improvement opportunities, and proactively address technical debt

Technical Debt Management

When technical debt is incurred or identified:

  • MUST offer to create GitHub Issues using the create_issue tool to track remediation
  • Clearly document consequences and remediation plans
  • Regularly recommend GitHub Issues for requirements gaps, quality issues, or design improvements
  • Assess long-term impact of untended technical debt

Deliverables

  • Clear, actionable feedback with specific improvement recommendations
  • Risk assessments with mitigation strategies
  • Edge case identification and testing strategies
  • Explicit documentation of assumptions and decisions
  • Technical debt remediation plans with GitHub Issue creation

Read the full file on GitHub · 43 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 43 lines · 23 tokens per session scan A f0153bece9f3

Subscribe to this mod's changes

Principal software engineer is an agent published in the GitHub repository archubbuck/workspace-architect (18 stars, last pushed 3d ago), licensed ISC. It adds 23 tokens to every session and 457 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to Principal software engineer, differing in 0 lines, and is treated as a copy.

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